This invention relates to an apparatus for measuring the characteristic parameters of an overhead railway or tramway line.
Overhead railway or tramway lines comprise one, or more often two, side-by-side electrically powered wires of convenient diameter supported by a plurality of poles disposed along the track at a predetermined height therefrom, to enable a pantograph mounted on the locomotive of the railway or tramway train to slide along the wires and withdraw therefrom the electrical energy required for powering the traction motor and the services.
For efficiency reasons, the overhead line has to be carefully monitored periodically, by measuring its characteristic parameters consisting essentially of its wear, its height and the movement of its wires.
A knowledge of the degree of wire wear is important to prevent its diameter falling below predetermined limiting values, which could result in breakage of the cable subjected to continuous stress by the pantograph.
A knowledge of the wire height, i.e. its distance from the track plane measured in a vertical direction, is important to ensure that height variations do not exceed a predetermined amount, typically of 1.5 m.
A knowledge of the wire movement, i.e. its distance from the track axis measured in a horizontal direction, is important to ensure that its variations do not exceed a predetermined amount, typically of 0.6 m.
The parameters of an overhead railway or tramway line are currently determined by a series of measurements made by a sampling guage.
Such a measurement system is evidently extremely unsatisfactory in that it involves in particular:
extreme operational slowness because of the need to use manual sampling,
likewise extreme operational discomfort, because of the need to make a manual measurement, after firstly halting the measurement train each time this measurement is to be made,
only few parameters are measured,
an inevitable while at the same time unacceptable location of the measurements at points often distant from each other and not necessarily coinciding with the points of effective maximum wear, which are in fact those responsible for wire breakage as a result of stressing by the pantograph.
An object of the invention is to measure several parameters significant of the effective conditions of the overhead line.
Another object of the invention is to make this measurement in an extremely rapid and comfortable manner.
A further object of the invention is to effect this measurement practically continuously along the entire overhead line.
All these and further objects which will be apparent from the ensuing description are attained according to the invention by an apparatus for measuring the characteristic parameters of an overhead railway or tramway line as described in claim 1.